The details often vary, but most streaming radio apps function in the same general way - cue up an artist station, start giving feedback in the form of "likes" and "dislikes," and let the app respond by giving you music that fits the profile of what you've told it you're into. The technology behind the scenes varies from app to app, but that's the basic idea.

Stereomood bucks that trend by classifying songs according to their mood, providing the listener with several playlists specifically tuned to certain emotions. Most of us would rather feel good, so the moods tend to skew positive - stations include "Romantic," "Dreaming," and "Just Woke Up." When they do go negative, as with playlists like "Asleep On My Feet" and "Feel Like Crying," it's always poetically so. We took it upon ourselves to find out whether we could get the thing a little more agitated. Where was the irksome music, the odes to being scared, stressed out and exhausted? If Stereomood is so good at making people feel a certain way, could it make me angry?

I fired up the new Stereomood mobile app (free for iPhone and Android) and began my quest for anger, finding the interface attractive if a little confusing. One page prompted me to select how it filtered "Stereotags" - a term that doesn't surface anywhere else in the app. I figured I'd tell it to filter them by mood, since that's supposed to be the focus of the app. "Choose your mood and start listening to create your emotional state of the week!" it told me, before redirecting me back to the home screen, without appearing to have changed anything. I listened some more, then tried again - no dice.

Perusing the list of mood-based playlists instead of working through the moods, the closest thing I could find to straight-up angry was one called "Gangsta." It appeared to be a catchall playlist for rap music, from self-identified thugs like Tupac and Biggie to backpacker types like Mos Def who'd probably bristle at the label. Also included, hilariously, is a track from noted non-gangsta Nick Cannon, the former Nickelodeon personality and current host of America's Got Talent.

Okay, so Stereomood haphazardly lumps any and all hip-hop music into a "Gangsta" playlist - that makes me angry for reasons I'd rather not go into here. But what about music that's pissed off by its very nature? I headed to the web version, which has a more-easily-browsable list of all available playlists. There, I found a more extensive list of moods, some of them pretty esoteric - Bible Study, Space Trip, State Of Hallucination - but the only playlist that overtly suggested music that might get me riled up was one simply titled "aggressive." Bingo.

I was expecting the kind of stuff that generally gets lumped under the "hard rock" umbrella, like distorted guitars, howling vocalists, and boneheaded sex metaphors, but was pleasantly surprised to find quite the opposite. Here were Evolver.fm staff favorites Pixies and The Men, alongside hardcore legends Fugazi, Black Flag, and Void.

True to Stereomood's philosophy of mood over genre, there were artists that didn't line up on the hardcore punk axis, but totally fit the vibe of the playlist: musicians like hip-hop slam poet Saul Williams, black metal lightning rods Liturgy, and 8-bit noiseniks Crystal Castles.

Thrashing around to these various stripes of aggro noisemakers, I felt a strange thing happen. I had finally found my playlist full of loud, intrusive, frustrated music, but I was delighted. I wanted to be angry, dammit! The whole time I had been searching for music to get me mad, and while I didn't find any, I did get sort of angry with the mobile version's clumsy design, and lack of attention to detail in the playlists.

When I finally did find the good stuff, I wasn't mad; I was satisfied.